The present invention relates to a device for adjusting digits in printers, particularly label printers.
Label printers are, for example, constructed in that a set of print wheels and a set of display wheels are coaxially positioned on a shaft. This shaft is axially movable through these wheels and two separate adjusting rings on the shaft can be coupled, respectively, to one display wheel and one print wheel so that upon turning of the shaft a particular digit on the one wheel indicates the digit that will be printed in that particular position. Upon axially shifting the shaft, the adjusting rings are coupled to the display wheels and the print wheels in sequence to adjust the entire set. A pair of sleeves on that shaft, respectively, hold wheels which are not to be turned; these sleeves are locked against rotation but the shaft can move them axially. However, due to the axial displacement of the sleeves on and with the shaft, one display wheel after another is not held any more without further measure.
The German Pat. No. 1,121,079 discloses a label printer of that type generally, and provides spring biased locks, being balls urged into recesses of the display wheels, to prevent them from turning when not coupled to an adjusting element. It was found, however, that such a position lock does not suffice. For example, excess ink or the like mixed with dirt may lodge in the gap between the (intended) independent wheels and couple them together.
German Pat. No. 1,259,909 and U.S. Pat. No. 3,427,961 suggest the provision of a further, third, sleeve which holds display wheels analogous to the holding as provided by the above-mentioned other two sleeves. The problem here is that that third sleeve structurally extends the device which is undesirable.